Manufacture of metal fluorides



Dec. 1, '1942.' c. ADAMoLl MANUFACTURE OF MTAL FLUORIDES Filed Sept. 16, 1938 INVENTOR v Car/o l4029/770/1 Patented Dec. 1, A1942v i r I i UNITED STATES PATENT OFFICE MANUFACTURE OF METAL FLUORDES Carlo Adamoli, Milan, Italy, assgnor to Perosa Corporation, Wilmington, Del., a corporation of Delaware Application september 1s, 193s, serial No. 230,334 In Italy September 18, 1937 6 Claims. (Cl. 23-88) application is a continuation-impart of The reaction between the hydroxide and the application Serial No. 172,870, led November 5, hydrofluoric acid gas is as follows: 1937, and relates to a process for the manufacture of anhydrous metal uorides free from con- BeHn-i'zHFTBeTZ'i-m-IZO stituents other than fluorine and metal. It'relates more particu1ar1y tc the manufacture ,of an 1s thus Obtslnedanhydrous metal uoride -from an oxide, a hy- It is likewise possible to cause the hydrouoric droxide, or a sulphide of the said metal, or to thel acid to react in the form of a continuous gaseous manufacture of a mixture of such nuorides sicurrent, which allows of the carrying out of a multaneously from oxides, hydroxides or sulphides Il' Particularly interesting mOduS operandi WhiCh of metals. v comprises the continuous action of a current of Thel invention is described below more eshydrofluoric acid ga's and gives a continuous propecially with respect to the manufacture of beduCtOn 0f' beryllium fluOIide. yItis mOleOVeI DOS- ryuium nuoride but it should be understood that sible, in this esse, to effect a constant and conit is broadlyapplieamefto the manufacture of tinuous introduction, in counter-current direcother metal fluoride or of a mixture of several tiOu, -Of beryllium hydroxide, Be(OH)2 in the liuorides, by applying reactions of the same kind DIOeeSS. l

as are herein described for the manufacture of It is else possible t0 intensify Jvue action 0f the beryllium uoride, hydrofluoric acid by subjecting to pressure the The physico-chemical conditions under which el mass which is under reaction; in fact, the operalt is possible t0 obtain the Compound of fluorine tion is eiected under particularly advantageous and beryuium which corresponds exact-,1y to the conditions when the hydrouoric acid is under formula. BeF2 are aheady known from an aca.' pressure in relation to the hydroxide or oxide of demic standpoint. Up till now, it has not been befylhums possible to industrially achieve'the manufacture '5 It iS likewise DOSSible t0 early Out the Operaof this fluoride except by the process .previously tion 0n the dry hydrated-Oxide 0f beryllium Prepatented by the appiicant, according to which the vieusly subjected te a compression (which perdon-ble uoride 0f beryuium and ammonium is mits of the reduction in volume of the reaction subjected to a heating process causing the distilvessel and of obtaining a smaller consumption of lation of ammonium fluoride, which is volatile, 3" thermal ehel'gyh and thus permitting the separation and recovery When other metal fiuondes than herylhum of beryllium fluoride BeFa.

In accordance with the present invention the 01' a sulphide 0f the metal Which iS t0 be C0111- said fluoride of beryllium BeF-a is prepared in an bihed with uorhe is used in Which Case the 0P- anhydrous state and free from oxide by app1y :i: eration is preferably carried out in a continuous ing industriauy under certain conditions which manner, as herein described.

' will be set forth below, the reaction of gaseous According t0 91 further feature 0f the invenhydrofluon'e acid, even inthe presence of Water, tion it .is as a rule better to carry out the reacon the oxides, bym-Oxides or sulphides of bel-y1- tion in the presence of an inert gas'such as car-. 1ium 4|' bon dioxide (C02) or Na, to prevent oxidation The process according to the invention melreactions and to ensure the removal of water fore'consists in the case of the manufacture of Vapu1`sformed by the reaction- The presence beryllium uoride, in causing to react in thel hot, Ofpoz 1S th? best methoq of avoldmg with ciel" on the oxide or hydroxide of beryllium, preferably l tamty the sk of formatmnf the oxyufmd in the dry state gaseous hydrouoc acid in the 4- It 1s advantageous to use an inert gas which 1s condensable and is not substantially soluble in dry or even non a'nhydrous staffe' but Wlth a Water water at atmospheric 'pressure as in that case, it content 1n any case not exceeding 20%.

can easil be se arat from th a r va r This hydrofluoric acid gas, acting advantay p ed e W te pou s developed by the reaction. This can be done by geously m a closed Vessel Charged Wlth the gas at 5l condensing the mixture of inertgas and water- -liolmal 01' Supma'tm"spheric Pressure is Supplied vapors produced by the reaction, and the inert in e quantity equal t0 0r exceeding that neceS- `gas may be dried and returned tov the reaction sary for the uorination of the quantity of berylvessel. lium oxide or hydroxide which has been intro- Concerning the temperature at #which it is duced in the Vessel- 55 Convenient to carry out the process, the said tem- A discontinuous production of beryllium uoride nuoride, areto be produced, an oxide,` a hydroxide.

perature should be high but care has to be taken that volatilisation of the beryllium fluoride which is formed is prevented. The temperature can be lowered to slightly below the melting temperature of beryllium fluoride, by which means the latter is obtained in a granular or spongy state, but not as a liquid. In most cases it is convenient to work at a temperature lower than '70D-'750 C.

It is best to use, in order to perform the reaction, vessels (tubes, furnaces or other vessels) constituted or protected, by means of materials such as for example fluorspar CaFz and/or the oxide of beryllium, or vessels made out of the very metal which is to be bound to the fluorine. When using non metallic material this should be employed in such manner that it forms a body or coating on the inner face of the vessel, which body or coating should be made very tight and compact in order to be impermeable and resistant to attack by the gaseous hydrofluoric acid.

In other words, the reaction is caused to preferably take place in a vessel covered with if not composed of, materials which owing to their nature and method of preparation, cannot be disintegrated or deteriorated by the gaseous hydroiluoric acid, and which are such that the beryllium uoride formed is not contaminated with other compounds during the process. All this is done by any means well known in the art.

It may be mentioned that, incertain cases, notably for producing beryllium fluoride in the presence of one or more fluorides of other metals, in particular the metals intended to be alloyed with beryllium, the reaction may be carried out in a vessel attackable by hydrofluoric acid, in such a manner as to produce the fluoride or uorides of the other metals in question. By this means it is possible to utilize for making the vessel or the coating of the same, materials capable of being attacked by the gaseous hydrofluoric acid at the temperature of the reaction.

It is likewise possible, with a view of obtaining in the same operation the production of beryllium fluoride and of fluorides of other metals, to perform the reaction of HF on a mixture of different metallic oxides, hydroxides or sulphides, in such a way as to produce, at the same time as the beryllium fluoride, fluorides corresponding to the metal or metals of the said metallic compounds.

As an example of the process; according to the invention, gaseous hydrofiuoric acid is caused to react on dry beryllium hydroxide placed in a tube of fluorspar or beryllium oxide maintained at a temperature of 'TO0-750 C. In this manner, the whole of the beryllium hydroxide is transferred completely into completely anhydrous beryllium fluoride free from oxide in the form of solid grains.

The accompanying drawing illustrates diagrammatically, parts being shown in section, an apparatus for carrying out the process in a continuous manner, thus avoiding any undue loss of heat and increasing the output of the apparatus. The following description relates to the treatment of any kind of starting material according to the invention but the operation will be more particularly described as applied to the manufacture of beryllium fluoride from beryllium oxide.

Referring more particularly `to the drawing, beryllium oxide stored in a trough I is delivered to a conduit 2 where the propelling screw 3 actuated by means of a pulley I delivers it to a through a -flue 8 into and through the helical' flue II surrounding the reaction vessel and escape through the chimney.

The reaction vessel 5 is provided with a propelling screw I2 which is rotated byv gearing I3, I4, the gear I3 being provided with a shaft I5 which passes through a conventional hydraulic seal I6. The screw I2 feeds the beryllium oxide through the reaction vessel 5 from right to left as viewed in the drawing and delivers it to a con` duit I1.

Hydrouoric acid gas is supplied to the conduit I1 through an inlet I8 and flows through the reaction vessel 5 in a direction counter-current to the passage of the beryllium oxide. The temperature in the reaction vessel is preferably from D-750 C. The hydrouoric acid gas may be supplied either in the dry state or when the temperature is as specified it may contain Water but not to exceed 20%. Thereaction converts the beryllium oxide into beryllium fluoride and the hot gases evolved from the reaction are led 01T from the reaction vessel through the outletj.

The beryllium uoride formed in the reaction vessel passes into the conduit I1 and falls into the conduit I9 provided with a valve 2l. Carbon dioxide or other inert gas is admitted to the conduit I9 through the inlet 22, in order to prevent oxidation of the beryllium fluoride. The valve 2| is opened from time to time and beryllium fluoride falls into the trough 20. When regulating the temperature in the reaction vessel 5 as above explained, the beryllium fluoride is ob.- tained in the conduits I'I and I9 in a. solid spongy or granulated form which facilitates its delivery from the apparatus. The carbon dioxide acts not only to provide an inert atmosphere in the apparatus but also being heavier than hydrofluoric gas displaces out of the granulated beryllium fluoride the gaseous hydroiluoric acid with which the beryllium fluoride is mixed. 'Ihe mixture of CO2 water vapors and hydrofluoric acid gas escaping through the outlet 6 can be passed to any suitable conventional condenser and dryer and the so recovered CO2 may be returned to the a.Dparatus through the inlet 22.

-What I claim is:

1. Process for obtaining beryllium fluoride in a substantially pure anhydrous state consisting in causing gaseous hydrofluoric acid to reac't at elevated temperature but below the melting point of beryllium fluoride on beryllium hydroxide, the starting materials being so dry and in such a proportion that the humidity of the gaseous hydrouoric acid in Contact with the beryllium hydroxide never exceeds 20%.

2. Process for obtaining beryllium fluoride in a. substantially pure anhydrous state consisting in causing gaseous hydrouoric acid to react at elevated temperature but below the melting point of beryllium fluoride and in the form of a continuous current of gas on beryllium hydroxide,

the starting materials being so dry and in such a.

5. Process for obtaining beryllium uoride in a substantially pure anhydrous state consisting in causing gaseous hydrouoric acidvto react at elevated temperature but below the melting point of beryllium fluoride in the presence of an atmosphere of gaseous carbon dioxide and in substantial amount and in a non-oxygenated atmosphere, on beryllium hydroxide, the starting materials being so dry and in such a proportion that the humidity of the gaseous hydrofluoric acid in Contact with the beryllium hydroxide nevcr exceeds 20%.

6. Process for obtaining beryllium fluoride in a substantially pure anhydrous state consisting in causing gaseous hydrofluoric acid to react at elevated temperature but below the melting point of beryllium fluoride in the presence of an at mosphere of nitrogen in substantial amount and.

in a non-oxygenated atmosphere, on beryllium hydroxide, vthe starting materials being so dry and in such a proportion-that the humidity of the gaseous hydroiluoric acid in contact with the beryllium hydroxide never exceeds 20%.

CARLO ADAMOLI. 

